Antihyperglycemic Studies on the Leaf Extract and Active Fractions of Newbouldia laevis (Bignoniaceae)

Abstract

Optimal control of chronic hyperglycemia prevents both micro and macro vascular complications—a leading cause of morbidity and mortality in diabetic subjects. This study was undertaken to give credence to the traditional use of Newbouldia laevis leaves in the treatment of diabetes mellitus (DM). Dichloromethane-methanol (1:1) extract (DME) of N. laevis leaves was prepared by cold maceration. Separation of DME into column chromatographic fractions yielded the n-hexane fraction (HF), ethylacetate fraction (EF) and methanol fraction (MF). The extract and fractions were evaluated for antihyperglycemic activity in alloxanized diabetic rats. The results showed that the oral administration of extract and fractions (250, 500, 1000 mg/kg) caused a significant (P < 0.5) and dose-dependent reduction in blood glucose level in diabetic rats. The hypoglycemic potency after 24 h was in the order MF (methanol fraction; 56.31%) > DME (dichloromethane/methanol extract; 36.19%) > EF (ethylacetate